Radio communications systems, such as Very High Frequency Communication (VHF COM) Systems, are often used in aircraft, such as General Aviation (GA) and Air Transport (AT) aircraft. A number of currently implemented VHF COM systems utilize three Line-Replaceable Units (LRUs) and three antennas, with each LRU being connected to its own dedicated antenna. These current systems (ex—3 antenna, 3 LRU, VHF COM systems) provide dedicated, independent voice communications for pilot and co-pilot as well as having one of the LRUs dedicated for data link operation. With such systems, simultaneous transmit and receive operation with any combination of the LRUs is desirable, so as not to restrict operation of any of the LRUs.
The above-referenced current systems (ex—3 antenna, 3 LRU, VHF COM systems) are typically configured so that two of the antennas are located on a top and bottom surface of an aircraft respectively (i.e., the “opposite side” antenna pair), while the third antenna shares either the top or bottom surface with one of the other two antennas (i.e., the “same side” antenna pair). The path loss isolation for the “opposite side” antenna pair may be 50+ dB, depending upon the size of an airframe of the aircraft. Given the power levels, transmitter noise floor, and receiver designs available in existing radio communication system products, very good simultaneous transmit and receive operation is possible for the “opposite side” antenna pair. In contrast, the antennas of the “same side” antenna pair, although typically spaced as far apart horizontally with respect to one another as is practical, may have a path loss isolation of 20 to 35 dB. Consequently, when using the “same side” antenna pair of current systems, only marginally acceptable simultaneous transmit and receive operation may be attainable, depending upon frequency separation and actual isolation between the antennas. A further problem with the existing systems (ex—3 antenna, 3 LRU, VHF COM systems) is that when configured on an aircraft, they tend to be cumbersome, resulting in unwanted weight and drag forces on the aircraft. Still further, a number of current systems may require utilization of complicated adaptive cancellation techniques in order to provide good simultaneous transmit and receive operation under various conditions (ex—normal or failed modes).
Thus, it would be desirable to have a system and method for providing radio communications which addresses the problems associated with current solutions.